The objective of this project has been to develop instrumentation and methodologies for quantitative determination of nanomole and possibly picomole amounts of materials of biological interest using field desorption (FD) and isotope dilution techniques. In the first two-year phase of this program, it was intended to develop a number of FD techniques and select the best of these for quantitative assay. To achieve the latter goal a CEC 21-110B double focusing mass spectrometer was modified to accommodate an FI-FD source. It was planned to use the integrating capability of the photoplate attachment for quantitative assay - to overcome the intrinsic fluctuations of FD sources. Most of the effort of the first year has been invested in the modification of the CEC mass spectrometer and in the development of ion sources.